Add note about testing inconsistency
Mitigates #56396
The true fix would be https://github.com/pytorch/pytorch/pull/75608 but there are many issues to debug and this is a good step forward to at least clarify.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75620
Approved by: https://github.com/kit1980, https://github.com/seemethere, https://github.com/malfet
